The present disclosure generally relates to downhole fluid flow control and, more particularly, to flow distribution assemblies for use in distributing fluid flow through well screens.
In the course of completing wellbores that traverse hydrocarbon-bearing formations, it is oftentimes desirable to inject fluids into the wellbore for a number of purposes. For example, gases, such as steam, are often injected into surrounding formations in order to stimulate the production of high-viscosity hydrocarbons. In other applications, an acidizing treatment fluid, such as hydrochloric acid, is injected into the wellbore to react with acid-soluble materials disposed in the formation, thereby enlarging pore spaces in the formation. In yet other applications, fluids, such as water or gas, may be injected into the surrounding formations in order to maintain formation pressures so that a producing well can continue production. In applications, the pressure of the water or gas is injected at a rate sufficient to ensure fluid production out a well head.
Injection operations are typically carried out by introducing an injection string into the wellbore to a desired location where the fluid injection is desired. The injection string oftentimes includes a wellbore screen or “sand screen” arranged thereabout. Injection of the fluid occurs through the sand screen, which serves to prevent the influx of sand or particulates back into the injection string during temporary breaks in the injection operation. In some instances, the sand screen may form part of a “modular” screen assembly in which the outflow (injection), flows from a controlled outflow point into and through an annular space between the filter media and the base pipe of the modular screen before passing through the filter media, rather than flowing directly through holes in the base pipe of the sand screen.
Following an injection operation, the injection string can also be used as a type of production string by reversing the flow of fluids and instead drawing fluids into the injection string from the surrounding formations. During such production operations, the sand screens are again used to filter sand and any wellbore particulates of a certain size from being entrained into the injection tubing (i.e., the production tubing).
Injection and production operations are typically performed at high flow rates, which can lead to the erosion or degradation of vital portions of the sand screens. More particularly, some well screen assemblies include discrete entry/exit points to/from the injection tubing. The flow of fluids being either injected or produced is naturally concentrated at these locations. Over time, fluid flow through the sand screens at these locations can cut or erode through the sand screens, and thereby render the filtering capabilities of the sand screen ineffective.